flow at lower revs. The new EXUP machine gave class leading pulling power from low revs, seamlessly, up to the red line at 11,500 rpm. It also allowed extremely radical high lift cams that gave a very lumpy idle when unplugged in the open position or when using a full aftermarket exhaust. Yamaha continued to use the EXUP valve system on the subsequent Yamaha YZF1000R Thunderace and Yamaha YZF-R1 motorcycles. Transmission The FZ1000 uses a five-speed sequential close ratio gearbox. The clutch is of the wet, multi-plate type and is hydraulically operated. Final drive is by O-ring chain and sprockets. Chassis The FZR1000 chassis provided the biggest advancement over the original Yamaha FZ750. A major reduction of frame weight resulted from the use of an all aluminum square section 'Deltabox' perimeter type frame. The frame consisted of cast and extruded sections, welded together and provided a large weight reduction, in region of a 40% over the equivalent steel frame.. Although first seen on Yamaha racing machines such as the FZ750 OU74 race machine and in use on other smaller capacity or racing motorcycles, this was the first use on such a large production motorcycle. Aluminum perimeter frames are now common amongst contemporary sports motorcycles. The new frame was complemented by large 41mm diameter Telescopic forks, cast aluminum hollow spoke wheels suitable for radial tyres. The 1989 redesign that resulted in the 'EXUP' bikes, provided a major refinement of the Deltabox frame, the more compact engine allowed a completely redesigned and smaller frame and along with the new 17" rear wheel and 43mm Telescopic forks. The machine was thus shorter, lower, stiffer and lighter than the previous model. The bodywork was also redesigned resulting in an almost new machine. In 1991 a further redesign resulted in the release of the FZR1000RU EXUP, upside-down telescopic forks were fitted and the front fairing was fitted with a single headlight, generally regarded to be the definitive FZR1000. By 1994 the machine reverted to twin headlights, although now 'Fox Eye' styled, braking however was improved with the fitment of six piston front brake calipers. MotorSport The 1000cc engine excluded the bike from the then popular Superbike racing class which limited four cylinder machines to 750cc, the bike was popular in open class racing in the hands of private teams. The bike won the Castrol Six Hour and Isle of Man TT Production class B in